Question

已知2x-y=10,求代数式[(x的2次方+y的2次方)-(x-y)的2次方+2y(x-y)]÷4y的值.

Answer 1

2x - y = 10

[(x^2 + y^2) - (x - y)^2 + 2y(x - y)]/(4y)

= [(x^2 + y^2) - (x^2 - 2xy + y^2) + 2y(x - y)]/(4y)

= [2xy + 2y(x - y)]/(4y)

= [2y(2x - y)]/(4y)

= (2x - y)/2

= 5